Scilab Function
Last update : April 1993

Signal - Signal manual description

### Filters

  - analpf: analog low-pass filter
  - buttmag: squared magnitude response of a Butterworth filter
  - casc: creates cascade realization of filter
  - cheb1mag: square magnitude response of a type 1 Chebyshev filter
  - cheb2mag: square magnitude response of a type 1 Chebyshev filter
  - chepol: recursive implementation of Chebychev polynomial
  - convol: convolution of 2 discrete series
  - ell1 mag: squared magnitude of an elliptic filter
  - eqfir: minimax multi-band, linear phase, FIR filter
  - eqiir: design of iir filter
  - faurre: optimal lqg filter.
  - lindquis: optimal lqg filter lindquist algorithm
  - ffilt: FIR low-pass,high-pass, band-pass, or stop-band filter
  - filter: compute the filter model
  - find_freq: parameter compatibility for elliptic filter design
  - findm: for elliptic filter design
  - frmag: magnitude of the frequency responses of FIR and IIR filters.
  - fsfirlin: design of FIR, linear phase (frequency sampling technique)
  - fwiir: optimum design of IIR filters in cascade realization,
  - iir: designs an iir digital filter using analog filter designs.
  - iirgroup: group delay of iir filter
  - iirlp: Lp IIR filters optimization
  - group: calculate the group delay of a digital filter
  - optfir: optimal design of linear phase filters using linear programming
  - remezb: minimax approximation of a frequency domain magnitude response.
  - kalm: Kalman update and error variance
  - lev: resolve the Yule-Walker equations :
  - levin: solve recursively Toeplitz system (normal equations)
  - srfaur: square-root algorithm for the algebraic Riccati equation.
  - srkf: square-root Kalman filter algorithm
  - sskf: steady-state Kalman filter
  - system: generates the next observation given the old state
  - trans: transformation of standardized low-pass filter into low-pass, high-pass, band-pass, stop-band.
  - wfir: linear-phase windowed FIR low-pass, band-pass, high-pass, stop-band
  - wiener: Wiener estimate (forward-backward Kalman filter formulation)
  - wigner: time-frequency wigner spectrum of a signal.
  - window: calculate symmetric window
  - zpbutt: Butterworth analog filter
  - zpch1: poles of a type 1 Chebyshev analog filter
  - zpch2: poles and zeros of a type 2 Chebyshev analog filter
  - zpell: poles and zeros of prototype lowpass elliptic filter

### Spectral estimation

  - corr: correlation coefficients
  - cspect: spectral estimation using the modified periodogram method.
  - czt: chirp z-transform algorithm
  - intdec: change the sampling rate of a 1D or 2D signal
  - mese: calculate the maximum entropy spectral estimate
  - pspect: auto and cross-spectral estimate
  - wigner: Wigner-Ville time/frequency spectral estimation

### Transforms

  - dft: discrete Fourier transform
  - fft: fast flourier transform
  - hilb: Hilbert transform centred around the origin.
  - hank: hankel matrix of the covariance sequence of a vector process
  - mfft: fft for a multi-dimensional signal

### Identification

  - lattn,lattp: recursive solution of normal equations
  - phc: State space realisation by the principal hankel component approximation method,
  - rpem: identification by the recursive prediction error method

### Miscellaneous

  - lgfft: computes p = ceil (log_2(x))
  - sinc: calculate the function sin(2*pi*fl*t)/(pi*t)
  - sincd: calculates the function Sin(N*x)/Sin(x)
  - %k: Jacobi's complete elliptic integral
  - %asn: .TP the elliptic integral :
  - %sn: Jacobi 's elliptic function with parameter m
  - bilt: bilinear transform or biquadratic transform.
  - jmat: permutes block rows or block columns of a matrix